A laser measurement system and method for the gap between a chip transfer carrier and a substrate.

Abstract

This invention relates to the technical field of precision chip measurement, specifically a laser measurement system and method for the gap between a chip transfer carrier and a substrate. The system includes a laser emitter, a transmission / reflection separation module, a displacement stage, and an imaging screen. In the laser measurement system for the gap between the chip transfer carrier and the substrate, the displacement stage is spaced between the transfer carrier and the receiving substrate. A first light beam and a second light beam are reflected and refracted and then reflected again by the transfer carrier and the receiving substrate, respectively. This results in multiple light spots being formed on the imaging screen by the first and second light beams. Furthermore, when the transfer carrier deflects or moves relative to the receiving substrate, the positions of the multiple light spots on the imaging screen change after reflection and refraction by the transfer carrier and the receiving substrate. The imaging screen measures the distance values ​​of each light spot after the change, thereby improving the accuracy of the gap measurement between the chip transfer carrier and the receiving substrate.

Description

Technical Field

[0001] This invention relates to the technical field of precision chip measurement, and in particular to a laser measurement system and method for the gap between a chip transfer carrier and a substrate. Background Technology

[0002] Micro-LED chip display technology boasts advantages such as high brightness, high contrast, low power consumption, fast response speed, and long lifespan, and is widely recognized by the industry as a crucial development direction for next-generation display technologies. The fabrication process for Micro-LED chip display panels is complex and involves numerous steps. Among these, the precise alignment and transfer of the Micro-LED chips grown on the carrier substrate to the receiving substrate is critical. Maintaining the consistency of the gap between the transfer carrier and the receiving substrate is crucial for achieving high-volume transfer, directly impacting the overall product yield and production efficiency. Therefore, it is essential to precisely measure the gap between the Micro-LED chip transfer carrier and the receiving substrate, and then feed this measurement back to the adjustment mechanism to achieve the required dimensional specifications, thereby improving the chip transfer yield and efficiency.

[0003] Typically, the gap between the transfer carrier and the receiving substrate needs to be controlled between 30 and 50 μm during the transfer process. When the gap between the transfer carrier and the receiving substrate is uneven, the transferred chip may become misaligned, flipped, or missing. In particular, if the carrier and the receiving substrate are not parallel, the chip may be misaligned during transfer. Precise control of the gap between the transfer carrier and the receiving substrate directly determines the yield and efficiency of laser mass transfer. Precise measurement of the gap between the transfer carrier and the receiving substrate is also a prerequisite for precise gap adjustment and a key to improving the yield and efficiency of laser mass transfer.

[0004] Due to the small gap between the transfer carrier and the receiving substrate, and the obstruction caused by chips with different arrangements, traditional contact measurement cannot achieve accurate measurement. There is an urgent need to break through the non-contact measurement method to measure the gap between the carrier and the substrate. Patent CN 116007515A proposes a method using a white light interferometric focusing system and demodulation to calculate the gap between the template and the substrate by utilizing the feedback spectral values. However, in measuring the transfer gap of Micro-LED chips, GaN-based Micro-LED chips absorb blue-green light, thus using spectral signals to measure the transfer gap will cause significant errors. Patent CN 115546172A proposes a method for measuring the transfer gap using machine vision, but this method is greatly affected by environmental factors such as lighting conditions and background noise, and it places certain requirements on the arrangement of the tested chips and the surface morphology of the tested substrate, making it difficult to meet the measurement needs during normal production. Patent CN 114623774A proposes a method for measuring the transfer gap using a combination of a light source and a photosensitive receiver, but this method can only achieve overall gap measurement between the two substrates, making it difficult to achieve small-scale gap measurement in specific areas on the substrate, and the installation of the light source and photosensitive receiver increases the complexity of the machine layout.

[0005] To address this issue, this solution presents a laser measurement system and method for the gap between a chip transfer carrier and a substrate. By irradiating the transfer carrier and the target substrate surfaces with a laser beam through multiple interfaces of refraction and reflection, the reflected light spot projected onto an imaging screen is measured multiple times with precision to achieve the measurement of the gap between the chip carrier and the substrate. Using a 650nm wavelength laser for irradiation avoids the problem of Micro-LEDs easily absorbing blue-green light signals, overcomes the limitation of single-point lasers in achieving range measurement, and effectively reduces the influence of external environmental factors such as illumination. This significantly reduces measurement costs while maintaining high accuracy, enabling high-precision measurement of the gap between the Micro-LED chip transfer carrier and the receiving substrate. Summary of the Invention

[0006] The first objective of this invention is to provide a laser measurement system for the gap between a chip transfer carrier and a substrate, which aims to solve the problem of high-precision measurement of the gap between the chip transfer carrier and the receiving substrate.

[0007] To address the aforementioned technical problems, a laser measurement system for the gap between a chip transfer carrier and a substrate is provided, comprising a laser emitter, a transmission / reflection separation module, a displacement stage, and an imaging screen. The transmission / reflection separation module includes a first lens, a second lens, and a reflector. The first lens and the second lens are offset perpendicularly. A portion of the laser beam emitted by the laser emitter is reflected by the first lens to generate a first beam, and another portion passes through the first lens to generate a second beam. The second beam is incident on the reflector and reflected by the reflector to the second lens, which then reflects the second beam, thus making the first and second beams parallel. The displacement stage has a transfer carrier and a receiving substrate placed at intervals. The first and second beams are reflected and refracted and then reflected again by the transfer carrier and the receiving substrate, respectively. After being reflected and refracted and then reflected again by the transfer carrier and the receiving substrate, the first and second beams form multiple light spots on the imaging screen, which is used to measure the distance between each light spot.

[0008] When the transfer carrier plate deflects or moves relative to the receiving substrate, the positions of the multiple light spots formed on the imaging screen after the first light beam and the second light beam are reflected and refracted and reflected again by the transfer carrier plate and the receiving substrate, respectively, change, so that the imaging screen can measure the distance value of each light spot after the change.

[0009] Furthermore, the reflector has a first reflective surface and a second reflective surface arranged vertically. After the second beam is incident on the first reflective surface at a first angle, it is reflected to the second reflective surface and then directed from the second reflective surface to the second lens at a second angle. The angle difference between the first angle and the second angle is 180°, so that the first beam and the second beam are parallel beams that are spaced apart and directed toward the displacement stage.

[0010] Furthermore, when there is local deformation on the surface of the transfer carrier plate or the receiving substrate, the position of the light spot formed by the first beam and the second beam on the imaging screen is different, so that the distance value of each light spot measured by the imaging screen is different.

[0011] Furthermore, the laser emitter includes a laser component, a collimating lens, a Galilean beam-shrinking assembly, and an aperture. The aperture is positioned away from the laser component, the collimating lens is located between the laser component and the aperture, and the Galilean beam-shrinking assembly is located between the collimating lens and the aperture.

[0012] Furthermore, the Galileo beam-shrinking assembly includes a convex lens and a concave lens, with the convex lens positioned near the collimating lens and the concave lens positioned near the aperture stop, to reduce the beam of the laser emitted by the laser component.

[0013] Furthermore, the laser measurement system for the gap between the chip transfer carrier and the substrate also includes an identification component and a data processing module. The identification component includes a camera and a filter lens located on the camera lens. The data processing module is electrically connected to the camera. The camera is used to observe the position information of the light spots on the transfer carrier and the receiving substrate and the light spot position information on the imaging screen. The data processing module is used to collect the position information of the light spots and light spots recorded by the camera.

[0014] The second objective of this invention is to provide a laser measurement method for the gap between a chip transfer carrier and a substrate, aiming to solve the problem of high-precision measurement of the gap between the chip transfer carrier and the receiving substrate.

[0015] To solve the above-mentioned technical problems, a laser measurement method for the gap between a chip transfer carrier and a substrate is provided, applicable to the aforementioned laser measurement system for the gap between a chip transfer carrier and a substrate, comprising the following steps:

[0016] S1. The transfer carrier and the receiving substrate are arranged on the displacement stage in a wafer stacking unit structure;

[0017] S2. Turn on the laser emitter and deflect the first lens, the second lens, and the reflector in the transmission-reflection separation module at an appropriate angle so that the first beam and the second beam are reflected on the surfaces of the first lens and the second lens, respectively, and then directed onto the transfer carrier plate and the receiving substrate.

[0018] S3. The first beam and the second beam are transmitted in the form of parallel light onto the wafer stacking unit composed of the transfer carrier and the receiving substrate. After reflection and refraction in the wafer stacking unit, the first beam and the second beam respectively form four reflected beams, which are projected onto the imaging screen to form light spots.

[0019] S4. Based on the camera capturing the light spots in the imaging screen described in S3, an image containing 8 light spots is obtained;

[0020] S5. Based on the data processing module, perform image processing on the light spot in S4, extract the center point and center coordinates of the eight light spots in the light spot image, and obtain the nonlinear relationship between the light spot on the surface of the transfer carrier and the receiving substrate and the center point of the light spot in the imaging screen in S3 through the calibration of the object point and the image point.

[0021] S6. Based on the laser reflection measurement, the lower surface of the receiving substrate is used as the reference surface. According to the center coordinates of the imaging screen spot in S3, the position coordinates of the light spot projected onto the upper and lower surfaces of the transfer carrier and the upper surface of the receiving substrate are derived and calculated.

[0022] S7. The displacement stage moves at a constant speed in the horizontal direction. The camera continuously takes pictures of the light spot and light spot images at a fixed frequency. The data processing module performs data analysis on the change in the center position of the light spot, calculates the thickness of the transfer plate and the receiving substrate and the change in the gap between them, and derives the deflection angle required for leveling between the transfer plate and the receiving substrate.

[0023] Further, let x be the distance between the light spots formed by the first beam or the second beam on the imaging screen. i Let d be the thickness of the i-th interface layer. i The following relation is satisfied:

[0024]

[0025] In the formula, i represents the number of layers measured (i = 1, 2, 3, 4...); θ i n represents the angle of incidence of the light ray on the upper surface of the i-th layer; i Let n represent the refractive index of the i-th layer, where n0 specifically refers to the refractive index of air.

[0026] Furthermore, when the transfer carrier plate deflects relative to the receiving substrate, the original spot spacing reflecting the thickness of the transfer carrier plate on the imaging screen is denoted as x1. After the transfer carrier plate deflects, the newly formed spot spacing reflecting the thickness of the transfer carrier plate on the imaging screen is denoted as x1'. The difference between the original spot spacing x1 and the newly formed spot spacing x1' on the imaging screen is Δx, which satisfies the following relationship:

[0027]

[0028] In the formula, Δx represents the difference between the original light spot spacing x1 formed by the imaging screen and the newly formed light spot spacing x1', α represents the deflection angle of the transfer carrier plate, with counterclockwise deflection being positive and clockwise deflection being negative; θ1 represents the incident angle of the light on the upper surface of the transfer carrier plate; n1 represents the refractive index of the upper surface of the transfer carrier plate; n2 represents the refractive index of the lower surface of the transfer carrier plate; and d1 represents the thickness of the transfer carrier plate.

[0029] Furthermore, when the transfer carrier plate deflects relative to the receiving substrate, it is leveled according to the difference Δx between the original spot spacing x1 formed by the imaging screen and the newly formed spot distance x1' of the imaging screen. When the Δx value is negative, the transfer carrier plate is rotated clockwise to level it; when the Δx value is positive, the transfer carrier plate is rotated counterclockwise to level it.

[0030] Implementing the embodiments of the present invention will have the following beneficial effects:

[0031] 1. In the laser measurement system for the gap between the chip transfer carrier and the substrate in this embodiment, since the transfer carrier and the receiving substrate are placed at intervals on the displacement stage, the first beam and the second beam are reflected and refracted and reflected again by the transfer carrier and the receiving substrate, respectively, so that the first beam and the second beam form multiple light spots on the imaging screen. Then, when the transfer carrier deflects or moves relative to the receiving substrate, the positions of the multiple light spots formed on the imaging screen after the first beam and the second beam are reflected and refracted and reflected again by the transfer carrier and the receiving substrate, respectively, change. The imaging screen measures the distance value of each light spot after the change, thus overcoming the problems of large measurement error and low measurement efficiency of the gap between the chip transfer carrier and the receiving substrate.

[0032] 2. In the laser measurement system for the gap between the chip transfer carrier and the substrate in this embodiment, since the reflector forms a first reflective surface and a second reflective surface that are vertically arranged, the second beam is incident on the first reflective surface at a first angle and then reflected to the second reflective surface. After passing through the second reflective surface, it is directed from the second reflective surface to the second lens at a second angle. The angle difference between the first angle and the second angle is 180°. Thus, the first beam and the second beam are parallel beams that are spaced apart and directed toward the displacement stage. When there is local deformation on the surface of the transfer carrier or the receiving substrate, the position of the light spot formed by the first beam and the second beam on the imaging screen is different, so that the distance value of each light spot measured by the imaging screen is different. This avoids the systematic error of measuring the transfer carrier or the receiving substrate with a single beam and improves the accuracy of the gap measurement between the transfer carrier and the receiving substrate.

[0033] 3. In this embodiment, the laser measurement system for the gap between the chip transfer carrier and the substrate includes a laser emitter comprising a laser component, a collimating lens, a Galilean beam-shrinking assembly, and an aperture. The aperture is positioned away from the laser component, the collimating lens is located between the laser component and the aperture, and the Galilean beam-shrinking assembly is located between the collimating lens and the aperture. The Galilean beam-shrinking assembly includes a convex lens and a concave lens. The convex lens is positioned closer to the collimating lens, and the concave lens is positioned closer to the aperture. This allows for beam shrinking of the laser emitted by the laser component, thereby constraining the size of the light spot formed on the imaging screen, determining the center coordinates of the light spot, and calculating the displacement of the light spot, thus improving the accuracy of the gap measurement between the transfer carrier and the receiving substrate.

[0034] 4. In this embodiment, the laser measurement method for the gap between the chip transfer carrier and the substrate is used because the transfer carrier and the receiving substrate are arranged on the displacement stage in a wafer stacking unit structure. The laser emitter is turned on, and the first lens, second lens, and reflector in the transmission-reflection separation module are deflected at appropriate angles, so that the first beam and the second beam are reflected from the surfaces of the first and second lenses respectively and then directed onto the transfer carrier and the receiving substrate. The first beam and the second beam are transmitted in parallel light onto the wafer stacking unit composed of the transfer carrier and the receiving substrate. After reflection and refraction within the wafer stacking unit, the first beam and the second beam respectively form four reflected beams, which are projected onto the imaging screen to form light spots. The camera captures the light spots in the imaging screen in step 3, obtaining an image containing eight light spots. The data processing module processes the data from step 3. Image processing is performed on the light spots in step 4 to extract the center points and coordinates of the eight light spots in the image. By calibrating the object point and image point, the nonlinear relationship between the light spots on the transfer carrier and the receiving substrate and the center point of the light spot in the imaging screen in step 3 is obtained. Then, based on the laser reflection measurement and taking the lower surface of the receiving substrate as the reference surface, the position coordinates of the light spots projected on the upper and lower surfaces of the transfer carrier and the upper surface of the receiving substrate are derived and calculated according to the center coordinates of the light spots in the imaging screen in step 3. The displacement stage moves at a uniform speed in the horizontal direction, and the camera continuously takes pictures of the light spots and light spot images at a fixed frequency. The data processing module performs data analysis on the changes in the center position of the light spots, calculates the thickness of the transfer carrier and the receiving substrate and the change in the gap between them, and derives and determines the deflection angle required for leveling between the transfer carrier and the receiving substrate. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the laser measurement system for the gap between the chip transfer carrier and the substrate as described in Embodiment 1 of the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of the laser emitter according to Embodiment 1 of the present invention;

[0038] Figure 3 This is a schematic diagram of the transmission and reflection separation module according to Embodiment 1 of the present invention;

[0039] Figure 4 This is a schematic diagram of the normal state of the wafer stacking unit described in Embodiment 1 of the present invention;

[0040] Figure 5 This is a schematic diagram of the structure of the reflector described in Embodiment 1 of the present invention;

[0041] Figure 6 This is a schematic diagram of the abnormal deflection of the wafer stacking unit according to Embodiment 1 of the present invention;

[0042] Figure 7 This is a flowchart of the laser measurement method for the gap between the chip transfer carrier and the substrate as described in Embodiment 2 of the present invention.

[0043] The components are as follows: 100, laser measurement system for the gap between the chip transfer carrier and the substrate; 110, laser emitter; 111, laser components; 112, collimating lens; 113, Galilean beam shortening assembly; 1131, convex lens; 1132, concave lens; 114, aperture; 115, first beam; 116, second beam; 120, transmission and reflection separation module; 121, first lens; 122, second lens; 123, reflector; 1231, first reflecting surface; 1232, second reflecting surface; 130, displacement stage; 131, transfer carrier; 132, receiving substrate; 1301, wafer stacking unit; 140, imaging screen; 150, recognition component; 151, camera; 152, filter lens; 160, data processing module. Detailed Implementation

[0044] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0045] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0047] Example 1

[0048] Please refer to Figures 1-6 Embodiment 1 of the present invention provides a laser measurement system 100 for the gap between a chip transfer carrier and a substrate, including a laser emitter 110, a transmission-reflection separation module 120, a displacement stage 130, and an imaging screen 140. The transmission-reflection separation module 120 includes a first lens 121, a second lens 122, and a reflector 123. The first lens 121 and the second lens 122 are offset and perpendicular. A portion of the laser beam emitted by the laser emitter 110 is reflected by the first lens 121 to generate a first beam 115, and another portion passes through the first lens 121 to generate a second beam 116. The second beam 116 is incident on the reflector 123 and passes through the reflector... The first beam 115 is reflected by the second lens 122, which reflects the second beam 116 to make the first beam 115 and the second beam 116 parallel. The displacement stage 130 is spaced with a transfer plate 131 and a receiving substrate 132. The first beam 115 and the second beam 116 are reflected and refracted and reflected again by the transfer plate 131 and the receiving substrate 132, respectively. After the first beam 115 and the second beam 116 are reflected and refracted and reflected again by the transfer plate 131 and the receiving substrate 132, they form multiple light spots on the imaging screen 140. The imaging screen 140 is used to measure the distance of each light spot. Specifically, the laser emitter 110 emits a horizontally collimated point laser with a spot size of 10–50 μm. This laser is a red laser with a wavelength of 650 nm. The first lens 121 is placed with a clockwise deflection angle of α. When the point collimated laser passes through the first lens 121, it is reflected and refracted on its surface. The reflected beam, the first beam 115, is directed towards the displacement stage 130 at a clockwise angle of 2α. The refracted beam, the second beam 116, continues to be emitted horizontally. After passing through the reflector 123, it rotates 180° and then passes through the second lens 122, where it is directed towards the displacement stage 130 at an angle of 180–2b. To ensure parallel beams, the first lens 121 and the second lens 122 are placed in the same position, and the deflection angles α and b of the first lens 121 and the second lens 122 are complementary. In addition, the transfer carrier 131 and the receiving substrate 132 form a wafer stacking transfer unit, which is used to present the positional relationship between the transfer substrate and the receiving substrate 132 during the mass transfer of Micro-LED chips. That is, the gap between the transfer carrier 131 and the receiving substrate 132 during the mass transfer of Micro-LED chips is 30 to 50 μm.

[0049] When the transfer carrier plate 131 deflects or moves relative to the receiving substrate 132, the positions of the multiple light spots formed on the imaging screen 140 after the first beam 115 and the second beam 116 are reflected and refracted and reflected again by the transfer carrier plate 131 and the receiving substrate 132, respectively, change, so that the imaging screen 140 can measure the distance value of each light spot after the change. In practical applications, since the displacement stage 130 is spaced with a transfer plate 131 and a receiving substrate 132, the first beam 115 and the second beam 116 are reflected and refracted and reflected again by the transfer plate 131 and the receiving substrate 132, respectively. This results in multiple light spots being formed on the imaging screen 140. Furthermore, when the transfer plate 131 deflects or moves relative to the receiving substrate 132, i.e., when the transfer plate 131 deflects relative to the receiving substrate 132, the angles of the first beam 115 and the second beam 116 after reflection and refraction by the transfer plate 131 and the receiving substrate 132 change. Moreover, when the transfer plate 131 deflects slightly relative to the receiving substrate 132, multiple light spots are formed on the imaging screen 140. The position of the light spot will also change significantly, so the distance value of each light spot after the change can be sensitively measured by the imaging screen 140, and then the deflection of the transfer carrier plate 131 relative to the receiving substrate 132 can be measured. Similarly, when the gap between the transfer carrier plate 131 and the receiving substrate 132 changes from 30 to 50 μm, the distance of the first beam 115 and the second beam 116 after reflection and refraction by the transfer carrier plate 131 and reflection and refraction by the receiving substrate 132 will change. The position of the multiple light spots formed on the imaging screen 140 will also change significantly. Moreover, the position change of the light spot with the change of displacement and deflection angle is independently distinguishable. That is, the spacing ratio of the light spots in the imaging screen 140 is different, and it is easy to identify the change of deflection or movement of the transfer carrier plate 131 relative to the receiving substrate 132.

[0050] In one possible implementation, the reflector 123 has a first reflective surface 1231 and a second reflective surface 1232 arranged vertically. After the second beam 116 is incident on the first reflective surface 1231 at a first angle, it is reflected to the second reflective surface 1232 and then directed from the second reflective surface 1232 to the second lens 122 at a second angle. The angle difference between the first angle and the second angle is 180°, so that the first beam 115 and the second beam 116 are parallel beams that are spaced apart and directed toward the displacement stage 130. In specific applications, since the reflector 123 has a vertically arranged first reflecting surface 1231 and a second reflecting surface 1232, the second beam 116, after entering the first reflecting surface 1231 at a first angle, is reflected to the second reflecting surface 1232, and then, after passing through the second reflecting surface 1232, is directed from the second reflecting surface 1232 to the second lens 122 at a second angle. The angle difference between the first angle and the second angle is 180°, so that the first beam 115 and the second beam 116 are parallel beams directed at the displacement stage 130 at intervals. It is worth noting that when the second beam 116 hits the first reflecting surface 1231 at different positions, the position of the second beam 116 reflected to the second reflecting surface 1232 is also different. That is, the width of the second beam 116 between the first reflecting surface 1231 and the second reflecting surface 1232 is different, so the width between the first beam 115 and the second beam 116 can be flexibly adjusted.

[0051] In one possible implementation, when there is local deformation on the surface of the transfer carrier plate 131 or the receiving substrate 132, the position of the light spot formed by the first beam 115 relative to the second beam 116 on the imaging screen 140 is different, so that the distance values ​​of each light spot measured by the imaging screen 140 are different. In practical applications, when there is local deformation on the surface of the transfer carrier plate 131 or the receiving substrate 132, if only one beam of light, such as the first beam 115 or the second beam 116, is used to measure the distance values ​​of each light spot (a set of light spots) on the imaging screen 140, then there will be a problem of low measurement accuracy if the first beam 115 or the second beam 116 happens to fall into the local deformation area of ​​the transfer carrier plate 131 or the receiving substrate 132. Therefore, two parallel beams of light (spaced a certain distance apart) are introduced, that is, the first beam 115 and the second beam 116 simultaneously form multiple light spots (two sets of light spots) on the imaging screen 140. Only when the distance values ​​of each light spot in the two sets of light spots are the same can the verification of the quality problems of the transfer carrier plate 131 or the receiving substrate 132 itself be improved.

[0052] In one possible implementation, the laser emitter 110 includes a laser element 111, a collimating lens 112, a Galilean beam-shrinking assembly 113, and an aperture 114. The aperture 114 is positioned away from the laser element 111, the collimating lens 112 is located between the laser element 111 and the aperture 114, and the Galilean beam-shrinking assembly 113 is located between the collimating lens 112 and the aperture 114. In specific applications, the laser element is mainly used to output a point-shaped red laser with a wavelength of 650nm; the collimating lens 112 is mainly used to collimate the laser emitted from the laser with a certain scattering angle for the first time, so that the laser propagates in a parallel beam in the horizontal plane; the aperture 114 is mainly used to further reduce the beam diameter to meet the measurement requirements for measuring the transfer gap of Micro-LED wafers; in addition, it can also eliminate stray light, reduce interference, and improve beam quality.

[0053] In one possible implementation, the Galilean beam-shrinking assembly 113 includes a convex lens 1131 and a concave lens 1132. The convex lens 1131 is positioned near the collimating lens 112, and the concave lens 1132 is positioned near the aperture stop 114, to reduce the laser beam emitted by the laser element 111. In specific applications, the Galilean beam-shrinking assembly 113 mainly reduces the parallel beam after the first collimation, ensuring concentrated propagation of beam energy, reducing energy loss after passing through the aperture stop 114, and facilitating subsequent laser imaging. The beam-shrinking process is as follows: After the first collimation, a relatively wide parallel laser beam enters the system. The laser beam first passes through the convex lens 1131 for beam shrinking. The function of the convex lens 1131 is to cause the beam to begin to shrink through the convex lens with a long focal length, but not to completely focus the beam to a single point. After passing through the convex lens 1131, the laser beam enters the concave lens 1132 for beam shrinking at a certain shrinking angle. The function of the concave lens 1132 is to use its negative focal length to counteract the focusing effect of the convex lens 1131 for beam shrinking, so that the laser beam is emitted horizontally with a smaller beam diameter.

[0054] In one possible implementation, the laser measurement system 100 for the gap between the chip transfer carrier and the substrate further includes an identification component 150 and a data processing module 160. The identification component 150 includes a camera 151 and a filter lens 152 located on the lens of the camera 151. The data processing module 160 is electrically connected to the camera 151. The camera 151 is used to observe the position information of the light spot and the light spot on the imaging screen 140 of the transfer carrier 131 and the receiving substrate 132. The data processing module 160 is used to collect the position information of the light spot and the light spot recorded by the camera 151. In specific applications, camera 151 is mainly used to observe the light spots on transfer carrier 131 and receiving substrate 132 and to capture the specific position and changes of the light spot on imaging screen 140. By monitoring the changes in the center position of the light spot and cooperating with the displacement module, continuous data acquisition is achieved, enabling accurate measurement of the changes in wafer gap height. Filter lens 152 is mainly used to filter out stray light interference and improve measurement accuracy. Data processing module 160 is mainly used to process the images acquired by camera 151, extract the coordinates of the center point of the light spot, and utilize the nonlinear relationship between the object point and the image point to convert complex laser reflection data into accurate thickness, gap, and leveling information.

[0055] In principle, a 650nm red laser is used as the measurement light source. The scattered laser emitted by the laser component 111 is shaped by the laser emitter 110 and emitted as a micro-beam horizontal laser. The size of the beam can be adjusted by changing the size of the aperture 114. After passing through the transmission and reflection separation module 120, the micro-beam horizontal laser can achieve oblique incidence of two parallel laser beams, which better ensures the parallelism and consistency of the laser. After the two laser beams are reflected on the surfaces of the transfer carrier 131 and the receiving substrate 132, the light spot is received by the optical imaging screen 140 and the light spot is identified and captured by the camera 151. This avoids damage to the camera 151 caused by direct laser irradiation and also ensures measurement accuracy. The measurement of two parallel laser beams can effectively reduce the displacement steps during platform measurement, reduce the need for manual intervention and mechanical errors.

[0056] Example 2

[0057] This embodiment differs from the subject matter protected in Embodiment 1, specifically as follows:

[0058] Please refer to Figure 7 Embodiment 2 of the present invention provides a laser measurement method for the gap between the chip transfer carrier 131 and the substrate, applicable to the above-mentioned laser measurement system 100 for the gap between the chip transfer carrier and the substrate, including the following steps:

[0059] S1. The transfer carrier 131 and the receiving substrate 132 are arranged on the displacement stage 130 in a structure of wafer stacking unit 1301.

[0060] S2. Turn on the laser emitter 110 and deflect the first lens 121, the second lens 122 and the reflector 123 in the transmission and reflection separation module 120 at a suitable angle so that the first beam 115 and the second beam 116 are reflected by the surfaces of the first lens 121 and the second lens 122 respectively and then directed onto the transfer carrier plate 131 and the receiving substrate 132.

[0061] S3. The first beam 115 and the second beam 116 are transmitted in the form of parallel light onto the wafer stacking unit 1301 composed of the transfer carrier 131 and the receiving substrate 132. After reflection and refraction in the wafer stacking unit 1301, the first beam 115 and the second beam 116 respectively form four reflected beams, which are projected onto the imaging screen 140 to form light spots.

[0062] S4. The camera 151 captures the light spots in the imaging screen 140 in S3, resulting in an image containing 8 light spots;

[0063] S5. Based on the data processing module 160, image processing is performed on the light spot in S4 to extract the center point and center coordinates of the eight light spots in the light spot image. Through the calibration of object point and image point, the nonlinear relationship between the light spot on the surface of the transfer carrier plate 131 and the receiving substrate 132 and the center point of the light spot in the imaging screen 140 in S3 is obtained.

[0064] S6. Based on the laser reflection measurement, the lower surface of the receiving substrate 132 is used as the reference surface. Based on the center coordinates of the light spot of the imaging screen 140 in S3, the position coordinates of the light spot projected on the upper and lower surfaces of the transfer carrier 131 and the upper surface of the receiving substrate 132 are derived and calculated.

[0065] S7. The displacement stage 130 moves at a constant speed in the horizontal direction. The camera 151 continuously takes pictures of the light spot and light spot images at a fixed frequency. The data processing module 160 performs data analysis on the change in the center position of the light spot, calculates the thickness of the transfer plate 131 and the receiving substrate 132 and the change in the gap between them, and derives the deflection angle required for leveling between the transfer plate 131 and the receiving substrate 132. In a specific application, the transfer carrier 131 and the receiving substrate 132 are fixed on the displacement stage in a wafer stacking unit 1301 structure; the laser emitter 110 is turned on, and the first lens 121 and the second lens 122 of the transmission-reflection separation module 120 are deflected at an appropriate angle so that the laser beam can be effectively transmitted onto the transfer carrier 131 and the receiving substrate 132 after being reflected on the surfaces of the first lens 121 and the second lens 122; the two laser beams are transmitted in parallel light onto the wafer stacking unit 1301 composed of the transfer carrier 131 and the receiving substrate 132. After reflection and refraction in the wafer stacking unit 1301, each laser beam forms four reflected beams, which are then imaged on the optical imaging screen 140; the laser spot in step 3 is captured by the camera 151 to obtain an image containing eight laser spots; the spot image in step 4 is processed by a computer. The process involves extracting the center points and coordinates of eight laser spots from the laser spot image. Through object point and image point calibration, the nonlinear relationship between the laser spots on the surfaces of the transfer carrier 131 and the receiving substrate 132 and the center points of the laser spots described in step 3 is obtained. Using the principle of laser reflection measurement, with the lower surface of the receiving substrate 132 as the reference plane, and based on the center coordinates of the laser spot as described in step 3, the actual position coordinates of the laser spot transmitted across the upper and lower surfaces of the transfer carrier and the upper surface of the receiving substrate 132 are derived. A displacement module is used for uniform displacement in the x-direction, and a camera 151 continuously captures and processes the laser spot image at a fixed frequency. A data processing module 160 analyzes the changes in the center position of the laser spot, allowing the calculation of the thickness and wafer gap changes of the transfer carrier 131 and the receiving substrate 132, as well as the deflection angle required for leveling between them.

[0066] In one possible implementation, the spacing between the light spots formed by the first beam 115 or the second beam 116 on the imaging screen 140 is denoted as x. i Let d be the thickness of the i-th interface layer. i The following relation is satisfied:

[0067]

[0068] In the formula, i represents the number of layers measured (i = 1, 2, 3, 4...); θ i n represents the angle of incidence of the light ray on the upper surface of the i-th layer; iLet n represent the refractive index of the i-th layer, where n0 specifically refers to the refractive index of air. In a specific application, a laser multi-reflection measurement system is built. The laser emitter 110 emits a micro-beam horizontal laser, the size of which is mainly determined by the pinhole aperture 114. In actual measurement, since the distance between the chips on the transfer carrier 131 and the receiving substrate 132 is about 70μm, a pinhole aperture 114 with a diameter of 50μm can be selected to ensure better measurement accuracy. The laser is first separated into a first beam 115 and a second beam 116 by the first lens 121 in the transmission and reflection separation module 120. The first lens 121 is deflected clockwise by an angle α. The first beam 115 is directed towards the wafer stacking transfer unit 1301 with a deflection angle of 2α, and the second beam 116 is directed towards the wafer stacking transfer unit 1301 with a deflection angle of 2α. The horizontal beam continues to propagate, and after passing through reflector 123, it achieves a 180° deflection on the horizontal plane. The reflected second beam 116 is reflected on the surface of second lens 122. Since the counterclockwise deflection angle of second lens 122 is b, the second beam 116 is directed towards wafer stacking transfer unit 1301 at an angle of 180°-2b. It can be seen that the angle 180°-2b is equal to the angle 2a. That is, when the relationship between a and b is complementary, the second beam 116 and the first beam 115 can form a horizontal laser beam directed towards wafer stacking transfer unit 1301 at the same angle. The laser is reflected and refracted in wafer stacking transfer unit 1301. According to the principle of laser reflection measurement, the laser spacing x can be deduced. i With the measured thickness d i The relationship between them is as follows:

[0069]

[0070] In the formula, i represents the number of layers measured (i = 1, 2, 3, 4...); θ i n represents the angle of incidence of the light ray on the upper surface of the i-th layer; i Let n represent the refractive index of the i-th layer, where n0 specifically refers to the refractive index of air.

[0071] In one possible implementation, when the transfer carrier plate 131 deflects relative to the receiving substrate 132, the original spot spacing reflecting the thickness of the transfer carrier plate 131 formed on the imaging screen 140 is recorded as x1. After the transfer carrier plate 131 deflects, the newly formed spot spacing reflecting the thickness of the transfer carrier plate 131 on the imaging screen 140 is recorded as x1'. The difference between the original spot spacing x1 and the newly formed spot spacing x1' on the imaging screen 140 is Δx, which satisfies the following relationship:

[0072]

[0073] In the formula, Δx represents the difference between the original spot spacing x1 formed by the imaging screen 140 and the newly formed spot spacing x1', α represents the deflection angle of the transfer carrier 131, with counterclockwise deflection being positive and clockwise deflection being negative; θ1 represents the incident angle of light on the upper surface of the transfer carrier 131; n1 represents the refractive index on the upper surface of the transfer carrier 131; n2 represents the refractive index on the lower surface of the transfer carrier 131; and d1 represents the thickness of the transfer carrier 131. In specific applications, the optical path when the transfer carrier 131 in the wafer stacking transfer unit 1301 is deflected can be determined according to the laser reflection principle:

[0074]

[0075] In the formula, Δx represents the difference between the original light spot spacing x1 formed by the imaging screen 140 and the newly formed light spot spacing x1' by the imaging screen 140; α represents the deflection angle of the transfer carrier plate 131, with counterclockwise deflection being positive and clockwise deflection being negative; θ1 represents the incident angle of the light on the upper surface of the transfer carrier plate 131; n1 represents the refractive index on the upper surface of the transfer carrier plate 131; n2 represents the refractive index on the lower surface of the transfer carrier plate 131; and d1 represents the thickness of the transfer carrier plate 131.

[0076] In one possible implementation, when the transfer carrier 131 deflects relative to the receiving substrate 132, the difference Δx between the original spot spacing x1 formed on the imaging screen 140 and the newly formed spot spacing x1' on the imaging screen 140 is used for leveling. When the Δx value is negative, the transfer carrier 131 is rotated clockwise to level it; when the Δx value is positive, the transfer carrier 131 is rotated counterclockwise to level it. In a specific application, the reflected laser beam after being reflected by the wafer stacking unit 1301 is transmitted onto the optical imaging screen 140 to form a spot. Each laser beam forms four spots arranged vertically. During the measurement process, the displacement stage 130 is operated to move at a uniform speed and with consistent step size along the x-direction, and the spot image is captured by the camera 151. The filter 152 can be a bandpass filter with a center wavelength of 650nm and a bandwidth of only 14nm. After the camera 151 has captured a sufficient number of light spot images, the data processing module 160 performs image and data processing. The processing mainly includes distortion correction, median filtering, threshold segmentation, and center position extraction. The wafer thickness and wafer gap of the transfer carrier 131 and the receiving substrate 132 can be calculated using the center position distance between the laser light spots, as well as the deflection angle required for leveling between the transfer carrier 131 and the receiving substrate 132. That is, the leveling is performed according to the difference Δx between the original light spot distance x1 formed by the imaging screen 140 and the newly formed light spot distance x1' of the imaging screen 140. When the Δx value is negative, the transfer carrier 131 is rotated clockwise to level it; when the Δx value is positive, the transfer carrier 131 is rotated counterclockwise to level it.

[0077] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A laser measurement method for the gap between a chip transfer carrier and a substrate, characterized in that, Including the following steps: S1. The transfer carrier and the receiving substrate are arranged on the displacement stage in a wafer stacking unit structure. S2. Turn on the laser emitter and deflect the first lens, second lens, and reflector in the transmission-reflection separation module at an appropriate angle so that the first beam and the second beam are reflected by the surfaces of the first lens and the second lens, respectively, and then directed onto the transfer carrier plate and the receiving substrate. The laser beam emitted by the laser emitter is partially reflected by the first lens to generate the first beam, and the other part passes through the first lens to generate the second beam. The second beam is directed onto the reflector and reflected by the reflector to the second lens to reflect the second beam, so that the first beam and the second beam are parallel. S3. The first beam and the second beam are transmitted in the form of parallel light onto the wafer stacking unit composed of the transfer carrier and the receiving substrate. After reflection and refraction in the wafer stacking unit, the first beam and the second beam respectively form four reflected beams, which are projected onto the imaging screen to form light spots. S4. Based on the camera capturing the light spots in the imaging screen described in S3, an image containing 8 light spots is obtained; S5. Based on the data processing module, perform image processing on the light spot in S4, extract the center point and center coordinates of the eight light spots in the light spot image, and obtain the nonlinear relationship between the light spot on the surface of the transfer carrier and the receiving substrate and the center point of the light spot in the imaging screen in S3 through the calibration of the object point and the image point. S6. Based on the laser reflection measurement, the lower surface of the receiving substrate is used as the reference surface. According to the center coordinates of the imaging screen spot in S3, the position coordinates of the light spot projected onto the upper and lower surfaces of the transfer carrier and the upper surface of the receiving substrate are derived and calculated. S7. The displacement stage moves at a constant speed in the horizontal direction. The camera continuously takes pictures of the light spot and light spot images at a fixed frequency. The data processing module performs data analysis on the change in the center position of the light spot, calculates the thickness of the transfer plate and the receiving substrate and the change in the gap between them, and derives the deflection angle required for leveling between the transfer plate and the receiving substrate.

2. The laser measurement method for the gap between the chip transfer carrier and the substrate according to claim 1, characterized in that, Let x be the distance between the light spots formed by the first beam or the second beam on the imaging screen. i Let d be the thickness of the i-th interface layer. i The following relation is satisfied: In the formula, i represents the number of layers measured (i = 1, 2, 3, 4...); θ i n represents the angle of incidence of the light ray on the upper surface of the i-th layer; i Let n represent the refractive index of the i-th layer, where n0 specifically refers to the refractive index of air.

3. The laser measurement method for the gap between the chip transfer carrier and the substrate according to claim 2, characterized in that, When the transfer carrier plate deflects relative to the receiving substrate, let x1 be the original spot spacing on the imaging screen that reflects the thickness of the transfer carrier plate. After the transfer carrier plate deflects, let x'1 be the new spot spacing on the imaging screen that reflects the thickness of the transfer carrier plate. Then, the difference between the original spot spacing x1 and the new spot spacing x'1 is Δx, which satisfies the following relationship: In the formula, Δx represents the difference between the original light spot spacing x1 formed by the imaging screen and the newly formed light spot spacing x'1; α represents the deflection angle of the transfer carrier plate, with counterclockwise deflection being positive and clockwise deflection being negative; θ1 represents the incident angle of the light on the upper surface of the transfer carrier plate; n1 represents the refractive index of the upper surface of the transfer carrier plate; n2 represents the refractive index of the lower surface of the transfer carrier plate; and d1 represents the thickness of the transfer carrier plate.

4. The laser measurement method for the gap between the chip transfer carrier and the substrate according to claim 3, characterized in that, When the transfer carrier plate deflects relative to the receiving substrate, it is leveled according to the difference Δx between the original spot spacing x1 formed by the imaging screen and the newly formed spot distance x1' of the imaging screen. When the value of Δx is negative, the transfer carrier plate is rotated clockwise to level it; when the value of Δx is positive, the transfer carrier plate is rotated counterclockwise to level it.

5. A laser measurement system for the gap between a chip transfer carrier and a substrate, characterized in that, The laser measurement method for the gap between the chip transfer carrier and the substrate as described in any one of claims 1-4 includes: Laser emitter; A transmission-reflection separation module, comprising a first lens, a second lens, and a reflector, wherein the first lens and the second lens are offset and perpendicular; A displacement stage is provided, in which a transfer plate and a receiving substrate are placed at intervals. The first beam and the second beam are reflected and refracted and then reflected again by the transfer plate and by the receiving substrate, respectively. An imaging screen is used to measure the distance of each light spot after the first light beam and the second light beam are reflected and refracted and reflected again by the transfer carrier plate and the receiving substrate, respectively. When the transfer carrier plate deflects or moves relative to the receiving substrate, the positions of the multiple light spots formed on the imaging screen after the first light beam and the second light beam are reflected and refracted and reflected again by the transfer carrier plate and the receiving substrate, respectively, change, so that the imaging screen can measure the distance value of each light spot after the change.

6. The laser measurement system for the gap between the chip transfer carrier and the substrate according to claim 5, characterized in that, The reflector has a first reflective surface and a second reflective surface arranged vertically. The second beam is incident on the first reflective surface at a first angle and then reflected to the second reflective surface. After passing through the second reflective surface, it is directed from the second reflective surface to the second lens at a second angle. The angle difference between the first angle and the second angle is 180°, so that the first beam and the second beam are parallel beams that are spaced apart and directed toward the displacement stage.

7. The laser measurement system for the gap between the chip transfer carrier and the substrate according to claim 6, characterized in that, When there is local deformation on the surface of the transfer carrier or the receiving substrate, the position of the light spot formed by the first beam and the second beam on the imaging screen is different, so that the distance value of each light spot measured by the imaging screen is different.

8. The laser measurement system for the gap between the chip transfer carrier and the substrate according to claim 5, characterized in that, The laser emitter includes a laser component, a collimating lens, a Galilean beam shrinking assembly, and an aperture. The aperture is positioned away from the laser component, the collimating lens is located between the laser component and the aperture, and the Galilean beam shrinking assembly is located between the collimating lens and the aperture.

9. The laser measurement system for the gap between the chip transfer carrier and the substrate according to claim 8, characterized in that, The Galilean beam-shrinking assembly includes a convex lens and a concave lens. The convex lens is positioned near the collimating lens, and the concave lens is positioned near the aperture, in order to reduce the laser beam emitted by the laser component.

10. The laser measurement system for the gap between the chip transfer carrier and the substrate according to claim 5, characterized in that, The laser measurement system for the gap between the chip transfer carrier and the substrate also includes an identification component and a data processing module. The identification component includes a camera and a filter lens located on the camera lens. The data processing module is electrically connected to the camera. The camera is used to observe the position information of the light spots on the transfer carrier and the receiving substrate and the light spot position information on the imaging screen. The data processing module is used to collect the position information of the light spots and light spots recorded by the camera.

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